There are many kinds of pressure-sensitive adhesives, which can be classified from different angles.
(1) the main component classification of press sensitive adhesives
Elastic body pressure sensitive adhesive
The elastomers used in this type of pressure-sensitive adhesives are natural rubber for a long time, and later they are gradually extended to various synthetic rubber and thermoplastic elastomers. According to the elastomer used, the pressure-sensitive adhesive can be further divided into natural rubber pressure-sensitive adhesive, synthetic rubber pressure-sensitive adhesive, thermoplastic elastomer pressure-sensitive adhesive.
A. Natural rubber pressure sensitive adhesive
This is a kind of rubber pressure sensitive adhesive which has been developed very early and still has a large output. They are natural rubber elastomer as the main body, cooperate with viscous resins, softening agent and stabilizer, fillers and additives including crosslinking agent (sulfide) complex mixture, due to natural rubber has both high cohesive strength and elasticity, and can very good miscibility with many viscosity resin, have high viscosity and good wettability of glued materials, so the natural rubber is ideal type of pressure sensitive adhesive main body material. Its main disadvantage is the existence of unsaturated double bond in the molecule, and its aging resistance to light and oxygen is poor. But its weatherability and heat resistance can be improved by crosslinking and using anti-aging agent. Almost all types of pressure-sensitive adhesives can be made with natural rubber pressure-sensitive adhesives.
B. Synthetic rubber and recycled rubber pressure sensitive adhesive
Pressure-sensitive adhesives made of styrene butadiene rubber, polyisoprene rubber, polyisobutylene and butyl rubber, neoprene rubber, nitrile rubber and other synthetic rubber as the main body, with adhesion-enhancing resin, softener, anti-aging agent and other additives have their own characteristics. But none of them are as important as natural rubber pressure-sensitive adhesives. Recycled rubber, especially the pressure-sensitive adhesive made of regenerated natural rubber also has good performance and relatively low price, so it is also paid attention to.
C. Thermoplastic elastomer pressure sensitive adhesive
Thermoplastic elastomers represented by styrene-butadiene-styrene block copolymer (SBS) and styrene-isoprene block copolymer (SIS) are the main raw materials for the manufacture of hot melt pressure-sensitive adhesives. Hot-melt pressure-sensitive adhesives, because they do not use solvents, will not produce environmental pollution and have high production efficiency. In today's society with increasing calls for energy saving and the elimination of environmental pollution, the importance of such pressure-sensitive adhesives is also increasing.
(2) Resin pressure sensitive adhesive This kind of pressure sensitive adhesive resin used are polyacrylate, polyurethane, polyvinyl chloride, polyethylene ether and so on. Among them, polyacrylate is used a lot, and its output has exceeded that of natural rubber pressure sensitive adhesive. [2]
A. Acrylate pressure sensitive adhesive
Acrylate copolymers prepared by copolymerization of various acrylate monomers are very important resin-type pressure sensitive adhesives. Compared with the above rubber pressure-sensitive adhesives, they have many advantages: colorless and transparent appearance and good weather resistance; Generally, it is not necessary to use adhesive resins, softeners and anti-aging agents and other additives to get good pressure-sensitive bonding properties, so the formula is simple; Pressure-sensitive adhesives with different properties can be prepared by copolymerization and crosslinking. Therefore, in the past 20 years, this kind of pressure-sensitive adhesive has developed very rapidly, and has replaced the dominant position of natural rubber pressure-sensitive adhesive.
B. Silicone and other resin-type pressure-sensitive adhesives are pressure-sensitive adhesives composed of silicone resin and silicone rubber, which have excellent high temperature resistance and aging resistance. It is a kind of special pressure-sensitive adhesives, and its main purpose is to manufacture all kinds of high quality pressure-sensitive adhesives.
Polyethylene ether is a kind of resin-type press-sensitive adhesive developed earlier, but its importance has been gradually replaced by acrylate press-sensitive adhesive.
In addition, ethylene. Vinyl acetate copolymer (EVA), polyurethane, polyester, polyvinyl chloride and other resins can also be prepared into a variety of pressure-sensitive adhesives.
(2) the morphological classification of pressure sensitive adhesive
Pressure-sensitive adhesives can be divided into solvent-based pressure-sensitive adhesives, water solution pressure-sensitive adhesives, emulsion pressure-sensitive adhesives, hot melt pressure-sensitive adhesives and rolling pressure-sensitive adhesives.
Emulsion type, solvent type and hot melt type pressure sensitive adhesives are dominant.
(3) whether the main polymer of the press sensitive adhesive is cross-linked
The pressure sensitive adhesive can be divided into cross-linked and non-cross-linked pressure sensitive adhesive. Crosslinking pressure sensitive adhesives can be divided into heating crosslinking type, room temperature crosslinking type, optical crosslinking type and so on. The cross-linked pressure sensitive adhesive has good bonding strength and is especially suitable for making long-term pressure sensitive labels.